Inductance is an electrical characteristic which is necessary to the operation of many circuits. For example, inductance and capacitance provide the necessary nonlinear characteristics for oscillators. When used in connection with transformers, inductance permits electrical signals to be coupled from one circuit to another without a physical connection therebetween. Transformers find a wide variety of applications including impedance matching, step-up or step-down, and DC voltage isolation.
Discrete inductors and transformers are made to satisfy numerous electrical parameters, such as power rating, breakdown voltage, inductance, resistance, size, weight, etc. Magnetic circuits of this type are well known in the art, and have been highly developed to satisfy almost any application. Thus, when a magnetic device of desired parameters is required, such a device may be readily obtainable. Generally, the discrete magnetic devices are assembled on circuit boards, or other similar electrical apparatus, and connected by wires to associated electrical devices. Hybrid circuits are also well known in the art, and include integrated circuits formed in conjunction with discrete electrical components.
In an effort to more fully utilize magnetic materials, magnetic films have been employed to construct high density memories. In this type of application, the X and Y conductor arrays are sandwiched between a planar nonlinear magnetic film and a planar linear magnetic material. The magnetic material proximate the intersection of the conductors defines the memory element which can be switched to a magnetized or nonmagnetized state during memory write operations. The conductors can also be accessed during read operations to detemine the magnetized state of the memory location. This type of memory is of the nonvolatile type, but was expensive to fabricate, could not be easily manufactured in large arrays and was not well suited for miniaturization. As a result, such types of memories have been superseded by semiconductor counterparts.
Another application for magnetic circuits includes inductive logic circuits. With this type of logic family, inductance is a required electrical characteristic in order to provide the conventional AND/OR logic functions. Because of the past inability to to readily fabricate inductive characteristics into integrated circuits, such logic family has fallen from use, and has been superseded by the bipolar and MOSFET transistor logic families.
From the foregoing, it can be seen that a need exists for a method of fabricating magnetic circuits with silicon integrated circuits to form monolithic circuits. An associated need exists for fabricating monolithic integrated magetic circuits using conventional silicon semiconductor processes.